The present invention relates to a fluid flow regulator for controlling the amount of fluid flow through the regulator and has specific application as a control valve for an internal combustion engine positive crankcase ventilation (PCV) system.
Existing PCV systems conduct crankcase blow-by gases to the intake manifold through a variable orifice valve, and the opening of this variable orifice valve is controlled by intake manifold vacuum. In existing PCV systems at high manifold vacuum the valve is closed; and a small orifice handles the flow. At manifold vacuums of 12 to 15 inches of mercury, the valve begins to open, thus increasing the flow capacity to handle the increased blow-by of the engine as the manifold vacuum decreases.
In the prior art PCV systems the valve is typically a mechanical valve having a tapered valve element that is spring loaded. The tapered valve element moves on and off the valve seat to an extent which is determined by the amount of intake vacuum to thereby provide the metering or regulation of the total amount of PCV gas flow in dependence upon the position of the valve element with respect to the valve seat.
The mechanical PCV valves of the prior art PCV systems present a number of problems.
The valve element itself is subjected to a great deal of mechanical abuse as it is moved back and forth and on and off the valve seat with changes in suction in the engine induction system. The PCV valve slams against the valve seat so hard that it tends to beat itself to death, and these valve elements therefore have to be made of specially hardened steel to provide any useful period of operation.
The mechanical operated PCV valve elements of the prior art also had a tendency to become gummed up by the PCV gases so as to cause sticking of the valve element on the valve seat. The gumming up problem can also cause a change of the orifice size prior to actual sticking; and both the changing of the orifice size and the actual sticking of the PCV valve caused substantial impairment of engine performance.
The prior art, mechanical type PCV valves also present maintenance problems. Major automobile manufacturers require that PCV valves be inspected every twelve months and replaced every two years.
It is a primary object of the present invention to construct a PCV flow regulator which provides a variable orifice valve function without any moving parts and which eliminates and avoids the problems of the prior art PCV valves.